Liquid control gear



June 14, 1949. c. G. HEBEL ET AL LIQUID CONTROL GEAR 2 Shee'ts-Sheet 1 Filed March '7, 1944 ATTOfPA ZY ,June14, 1949. c. G. HEBEL ElAL 2,473,282.

LIQUID CONTROL GEAR Filed March 7, 1944 2 Sheets-Sheet 2 lillllllllill jj lj a ATTORNEY Patented June 14;, 1949 LIQUIDCONTROL GEAR Carl G. Hebel', Weehawken, N. J., and Robert-H;- Wallace, Central Nyack,. N. Ye, assignors: to Sperry Products, Inc Hoboken, .N. J a, cor,- porationofNew York" Application March 7, 1944; SerialiNo:.52'5,344'

9 Glaims. 1

This invention relates-to liquid control gear of thetype wherein movement of a member at a transmitting station is causedto control movement of a member ata receiving station. More particularly, this invention relates tov control gear of this type wherein the transmitting and receiving stations are connected by. a liquidtransmission system. One such system is shown In the" patent to H. S. HeleShaw and T. E. Beacham, No. 1,983,884,, granted December 11,

1934; in whichthe object is to apply a constant force to the fluid systematthe transmitting end and to receive a correspondingconstant force at the, receiving end. Another such system is shown in the-patent to Alfred N. Lawrence, No. 2,197,554, granted April: 16, 1940, for Liquid control gear, inxwhichthe object consists in applying a constantlyincreasing force at the transmitting end to overcome a constantly increasing load at'the operated or receiving end; In either of the aforementioned cases, the operating and operated members will retainany position into which they may bemoved" without any tendency on their part toreturn to a centralized position.

In this type of transmission system aproblem arises due to the fact that the fluid in the transe mission system changes its temperature, particularly at the receiving end, due to the operation ofthe-mechanism at that end, and such change is ata greater rate than that of the pipe in which the transmitting fiuid iscontained; As a result, the parts at the receiving end are operated through a predetermined degree greater or less than the operation- Which has beentransmitted thereto bythe transmitting end; Thus, for instance, it has been found incases where the receiving endvis employedto operate a variable pitch propeller mechanism under controlv of a governor, that the temperature variation due'to heating up of the fluid at the receiving endhas caused variation in engine speed up to 200 R. P:.M.

It is therefore one of the principal objects of this invention to provide a transmission system of the type described wherein the relationship between the transmitter and the receiver will not be affected by temperature variations. For this purpose there-is provided in the connection between the transmittingstation and-the receiving station a temperature compensating means provicling for automatic variation of the volumetric capacity of the, said connection in accordance with temperature variations. These variations in volumetric capacity are designed to be-exactly; sufiicient, to take; care of the. increase; or

2; decrease of volume; of the fiuid inthe transmission -system.-,

It. isra furthen object of; this invention to provide-Vin connection with the temperature comp ensating-i means mentionedin the foregoing paragraph, anemergency, connection which is designed -to connect the f transmitting station and the receiving-station in'theeve'nt that the main connection fails.

It is-:a further object ofthisinvention to provide temperature? compensating means of the type: mentioned above which does not" prevent operation of the liquid contro1 system in the eventthat the, temperature compensator failsby reason of: the-breaking V of-the emergencyline.

Further objects and advantages of this invention Willbecome apparentin the following detailed description thereof.

In the accompanying drawings,

Fig. l is an assembly View; with-parts sectioned vertically-r, of a-liquid controlgear embodyingour invention.

Fig, 2-is a; diagrammatic I detail showing other operating positions of the compoundvalve emlayed in Fi Fig; 3isa=viewof-aitransmitter assembly showinga'm-odification o-fithe form disclosedin Fig. 1'.

Referring tothe drawings, it will :be seen that this invention-compriseswthree main parts, name- 1y ail-transmitting; station A; a receivingstation B, and a forcetransferring connection which maycomprise a' -plurality of ducts C, D and E with a temperature compensating means indicated generallyat: E interposed "insaidline; The conn eotionsG, D, F, E are-filled with liquid so that force applied-at one, end'of; the liquid column at C will cause-; said column tomove throughthe connections to operatea member at the outer endof-- duct-E; Forrapplyingforcesto the liquid column for the purpose of transmitting forces, thereemay be provided zapc-ylinden I 0, within which operatesazpistorr H: Saidrcylinder is:-connected at one end t-o theduct- C-which: isfilled with liquid extending-up tolsaid-piston. For operating the said,- piston in a: direction-itotransmitforce to the liquid column, therezmay -be-provided-a transmitting elementin the'form'of'a lever Mpivoted within the casing- I'Br' on a pivot H, and having an operating handle l5- and the leveror crank arms. l8 and? I 8. The-crank arm portion [8 is pivotallyi connected? at 153- tothe upper; end of a pistong ro d 20:'pivotally connected: to the piston atv 2 As 1 the handle; is moveddna the direction of-l the; arrow; the piston, is lowered to cause the cnlum-nz of 'liquid to move; through the:- duct: C;

The force which is applied to the piston is determined by one or more loading springs 22 seated at one end against the bracket 23 fixed upon the sleeve 2 pivoted at 25. The other ends of said loading springs bear against a bracket 25 fixed to a rod 28 which operates within the sleeve member '24. The springs are under compression and apply the operating force to the lever arm I8 by way of the pivotal connection 29 between the upper end of rod 28 and the operating lever I4. The distance between the center of pivot I! and the center of pivot 29 forms the crank arm I8 through which the force is applied. The positions of the springs and their connections are such that the springs act through a small lever arm to apply a relatively light loading force to crank arm I8 and the piston II when the piston is in its uppermost position, but as the handle I is actuated in the direction of the arrow, it will be seen that the springs act through an increasing lever arm. At the same time, however, the springs are extended so that while they act through a larger lever arm they apply a decreasing force to said arm as the latter increases. The design of the various parts may be made such that the rate of decrease of the compressive force of the springs is equal to, or slower than, the rate of increase of the lever arm as handle I5 is actuated in the direction of the arrow, depending upon the purpose to which the device is to be put, that is, Whether the product of these two factors should be a constant to yield a constant loading force, or whether said product shall yield a continuously increasing loading force. In either case the force which an operator applies to handle I5 is constant in spite of the increasing force on the piston and need only be sufiicient to overcome friction in the system. The operation of handle I 5 at the transmitting station just described to move piston I I inwardly in its cylinder will cause an ment 24', 28 being similar to the element 24, 28

at the transmitting end. The two parts similarly hold between brackets 23' and 26' a set of compression springs 22' similar to springs 22. The distances between pivot I1 and pivot I9 and between IT and 29' are the same as between pivot I1 and pivots I9 and 29. Thus it will be seen that the relationship of the parts at the transmitter and receiver are the same but in inverse order, and therefore a force transmitted by movement of piston I I will produce an equal movement of piston II'. An operating member or handle I5 fixed to move with lever I4 will therefore move in parallel relationship to handle I5 in whichever position handle I5 is placed.

The casing I6 is provided with a liquid reservoir in order to maintain the transmission system filled. The leakage from said system may be replenished by connecting the said cylinder by way of passage 30 and valve 3| to the liquid within the casing I6. This may be done by depressing said valve 3| against the action of spring 32 by means of a rod 33 fixed to said valve, said rod being adapted to be engaged by means of a crank 34 pivoted at 35, said crank being actuated by a pin 36 when the piston I I is in its uppermost position. At this time the engagement of pin 36 rocks the bell crank around its pivot 35 to cause it to engage rod 33 and open valve BI to permit liquid from the reservoir to enter the cylinder II].

When there is variation of temperature which may afiect the fluid in the transmission system, the liquid will tend to expand or contract, and thus operated member I5 will tend to change its relationship with respect to operating member I5. An error in the transmission system is thus introduced and, as stated hereinbefore, Where the operated member I5 is a governor control it has been found that such temperature variations may cause variations in the engine speed of as high as 200 R. P. M. The problem therefore consists in devising a system whereby the variations in temperature of the fiuid in the transmission system will not affect the relationship of the operating and operated elements. For this purpose we have provided the following solution:

In the fluid connection C, D, E there is interposed the temperature compensator F designed to provide a variable volumetric capacity to the fluid connection in response to temperature changes, and to a degree corresponding to the amount of contraction or expansion of the fluid in the system. The variable volumetric capacity is supplied by means of a variable chamber 48 formed within the casing M of the temperature compensator. Said chamber 40 has a fixed wall 42 at one end and a movable piston 43 at the other, so that the position of the piston defines the size of the chamber. The duct D communicates with chamber 40 by way of a chamber Al and port 45 while the duct E communicates with chamber 40 through port 46. The fluid connection from transmitting station A to receiving station E therefore includes the ducts C and D, chamber 44, port 45, variable chamber 40, port it and duct E.

It will now be seen that if the variable chamber 40 could have its volume varied in one direction or the other corresponding to the total increase or decrease in volume of the liquid in the force transmitting connection between A and B, there would be no undesired operation of either the transmitter handle or the receiver element in response to temperature variations. To accomplish this result we provide an auxiliary fluid connection G extending from a port in the compensator housing M to a valve 5| which connects the other end of the line G to the duct C. The valve 5I is normally positioned so as to disconnect the line G from duct C. The other end of line G enters the housing 4| through port 59 into a chamber 52 in which is positioned a piston 53 normally abutting against a stop 49, and thence by way of a port 54 into a chamber 55 in which operates a piston 56. The volume of fluid in line G, chamber 52, port 54 and chamber 55 is made equal to the volume of fluid in the duct C. duct D, chamber 44, port 45, chamber 48 and duct E. Further- .more, the line G is drawn substantially parallel length adjacent the transmitting station.

ofithejfact that-pistons 43 and 55:a1'e; rigidly-connectedjby means; of a: rod 60. fluid-in;thecompensator line: expands, piston, 56 will be moved, to the left to move piston .43-to the left,.andthus increase the volume of chamber 411: byan amount equall to the expansion of the liquidfin line C, D, E' because the liquid in said mainline C, D,,E is equalin volume to the liquid in compensatorline G. Similarly, when contraction occurs due 1 to lowering oftemperature,

the liquid-in line G-contractsand enables a spring, system 62 housed within a chamber 63 to. forcepiston 54 to the left andoperate a lever 65 around its pivot 65 to-move. piston, 435110 the. right byreasonof its connection 61 tosaidilever. Thus, the

volume of chamber 40 is diminished, and to the extent exactly; equal to the reduction. in volume in -main line C, D, E because such reduction is equal to, that of; the lic 'id. in compensator line G. The springs 22 and 22 maintain the fluid in the main line C, 11E under a predetermined pressure, but the spring assembly 62 is designed to exert a pressure on-piston 43 far in eXcess of any pressures encountered in the system due to operation under normal loads. In. other words, the compensator piston 43 cannot be moved to vary the volume of chamber 40 by the pressure in the fluid transmission system due to operating under any loads within the rated output of the liquid control gear. at one end by. the valve 5|, there is an incompressible body; of fluid at the right end of piston 55which holds it against any. movement except that due to contractionor expansion of the fluid in the compensator system. The tension of the spring system, 62 may be adjusted inany. suitable manner, as by means of a threaded nut 68.

The above described temperature compensation system can be utilized to provide analternative emergency fluid connection between transmitting, station A and receiving station B in the event that the main duct D fails. It will be understoodthat. D provides the principal length of duct between stations, the temperature compensator F being located adjacent the receiving station, andthe duct C being of relatively short For this purpose, the compensator duct G may be utilized by providing suitable connections at its ends to the ductC and the duct E respectively. The connection to the duct C may be accomplished' manually. by the'operator when he realize-s that the ducti D has been broken,.and for this purpose a valve H may be operated to disconnect the duct D from duct C" while at the same time valve 51 may be operated to connect one end. of compensator duct G to the duct C.

The other end. of compensator duct G may be connected to ductE automatically when valve 5| is. operated toconnect compensator G to duct C. When. this occurs, the. fluid contained in chamber 55, port 54, chamber, 52-, port 50, and compensator duct G, isv nolonger an incompressible body of fluid, but is now connected toduct C and hence to the .tran-smission-system. The pressureof spring. system 62.'may. therefore operate the piston 43, to the righttoclose port 45.and to move piston 56 to-therightand displace the fluid. from. chamber: 55. until.- a port 12 in piston 56 registerswith. a port lileading to duct E. That is, communication is established. from. duct E throughport 1.3, port 12, port. 54, chamber 52, port 50,,compensator duct G, valve 5|, duct C to the transmitting station, and by dllctzEttQ-thergceiving; tation. Thus; a

Thus, when, the

Since compensator line G is closed fluid. connection: has: b.een-.establishedby wayof compensator G with. original main: duct Dcut out. Under: these conditions, theliquid control gear may operate to transmit movement, but obviously the temperature compensation system nolongen functions. The liquid control gear is now under: emergency operation, and for the period of such. Operation it will be subject to whatever temperature-errors may be introduced.

While duct-'D-functions, and the compensator systemis effective, that is, with valve H con.- necting'duct. D to duct C, and-valve 5| disconnectinge duct G from-duct C, in other words, withthe parts asshownin Fig. 1, it may occur that the? duct Gwillfail. Under these circumstances provisionis made; whereby the system will be operated as: aliquid control gear to transmit motion from'station A to station B, but without the, benefit of temperature compensation. In other word-s,,failure of the temperature compensator will not interfere with the operation ofthe force transmitting system. To make this effective; it will be seen that failure of duct G would: release" the pressure in chamber 55 and permit the spring system 62 to move piston 43, and hence piston 5.5-to the right. When piston 5.6:strikesthewwallot chamber'55, piston 43 will stop. just: short of port 46= and port 16 in the same plane. Sincethe pressure has dropped in chamber 52, the pressure of the liquid control systemin chamber 44 will be suflicient to operate piston 53 to theright to close port 54 and open port'ifi. Closure of port 54 will disconnect duct E and port 12 from duct G. Duct E will be able to communicate with chamber 44 through duct 45 and port 16, duct 45 having been closed by the movement of piston 43 to the right. Thus, the fluid connection is maintained between the transmitting station and the receiving station through duct C, valve ll, duct D, chamber 44, port 15, chamber 40, port. 46, and duct E, even though the pressure in the compensator duct G has failed. Therefore, normal operation of the liquid control gear is possible; without, however, receiving the benefit of temperature compensation.

Heretofore there has been described a system where, upon failure, of the main duct D, compensating line G acting as an emergency line is automatically connected at the receiver end into the main transmission line and is connected into this same line at the transmitter end by hand operation of valves 5! and H. By valve H duct D is disconnected, and by valve 5|, duct G is connected into the main. transmission line between A and B. In. Fig. 3 there is disclosed a system whereby line G may. be automatically connected at both ends into the main line connection between A and B upon failure of main duct D.

For. this purpose, a modified form of transmitter A issubstitutedfor. transmitter A of Fig. 1. Instead of the transmitter casing being connectedto lines D and G, as shown in Fig. l by way of valves 5|. and H outside of the case, in the Fig. 3 form the fluid in cylinder I0 is connected to the lines D and G by way of a valve structure incorporated into the casing of the transmitter in the lower portion thereof, The upper portion of transmitter A is similar in all respects to the mechanism. in transmitter A, and similar parts are similarly numbered. The valve structure which takes theplace of valves 5| and H inthelower portion of the transmitter casing comprises a slide valve flflwhich normally is positioned toprovide, communication between, cylinder I and duct D, while cutting off communication between cylinder I0 and duct G. This normal position of valve 80 is shown in Fig. 3 wherein it will be seen that the passage 8| from cylinder I0 is in open direct connection with the duct D, whereas, the connection betweencylinder I0 and duct G, which normally comprises passage 8|, passage 82, passage 83 and passage 84 is closed by the valve 89.

As described in connection with Fig. 1, the pressure in the line G is much greater than the pressure in the line D because of the spring system 92, and therefore, the pressure in chamber 85 into which duct G opens would normally tend to operate slide valve 89 to the left until the left hand end 86 of the valve engaged stop 81, and caused a block portion 88 on the valve to cut off communication between cylinder IOand duct D, while opening communication between cylinder I9 and duct G by way of ducts 82, 83, 84 and chamber 85. This, however, is normally prevented by means of a pin 99 engaging'to the left of piston portion 91 of the valve 8|), and thus preventing movement of said valve to the left. Pin 99 is carried by a piston 92 having a rod 93 slidable in the fixed casing, and pressure is applied to the upper end of said piston 92 by means of the fluid from cylinder l9 and passage 39. This is normally sufficient to overcome the pressure of spring 94.

Normally, therefore, the parts are as shown in Fig. 3 with the duct D forming the main transmission line between cylinder I8 and cylinder I9, while the duct G performs its compensating function as in Fig. 1. When duct D fails, however, pressure on piston 92 is relieved, and spring 94 is enabled to lift pin 99 out of engagement with piston part SI of valve 88, thus permitting the pressure in chamber 85, which it receives from duct G, to move the valve 80 to the left, causing piston portion 88 to disconnect cylinder ill from duct D. At the same time, communication is established between cylinder Ill and duct G through passages 84, 92, B3, 84 and chamber 85. The valve 89 is provided with drainage channels 99 and Hill connected by a central bore 97, said channels 95 and IIlI being adapted to drain through opening 98 when the slide valve 89 is at either end of its stroke.

Connection of duct G to cylinder it! acts in the same way as the opening of valve in the Fig. 1 form, and serves to connect duct G by way of the compensator mechanism F to line' E.

Thus, it is apparent that failure of duct D will result in automatically connecting the duct G to the transmitting cylinder and to the receiver cylinder to establish a. through-force transferring connection. The temperature compensating feature, however, is lost. On the other hand, if the duct G should fail while duct D still functions, this would not affect the operation of the main force transferring line, but would only result in the elimination of the temperature compensating feature. Upon failure of duct G, the pressure in chamber 85 would be relieved, which would enable spring Hill to move slide valve 89 to the right until it strikes the end of the chamber, at which time the piston portion 9| of the slide valve would cut off line G from passage 84, and hence from cylinder I9. We have seen that maintaining the connection of cylinder ill to duct D effective, and to duct G inefiective, depends upon maintaining pressure on the piston 92 sufficient to overcome the pressure of spring 94. However, upon synchronization at the end of a stroke of the piston II, the pressure in the'system is relieved, which would, unless measures were taken to prevent it, release the pin 99 to permit pressure from duct G in chamber to operate the valve to the left, and thus cut off the main force-transferring connection through duct D. To obviate this condition there is provided a bell crank I85 pivoted on the frame at I08 and normally spring-pressed by a spiral spring I II connected to the pivot and the bell crank so as to swing the bell crank with its arm I99 directly overlying the piston rod 93 to prevent the piston 92 and the pin 99 from lifting. When the piston II is at the upper end of its stroke, the pin 39 engages the bell crank 39 to move'the rod 33 downwardly and open the valve SI, permitting fluid from the reservoir to communicate with the fluid in cylinder I9. Such downward movement of rod 33 does not affect the position of bell crank I05 because a pin I01 on rod 33 is free to ride downwardly within a slide I98 formed in the bell crank. When the piston I I approaches the lower end of its stroke, a pin 36 engages the'bell crank 34 to lift rod 33, and hence, lift pin I9! to cause the bell crank I95 to rock in a clockwise direction around its pivot I96 to permit arm I99 to move off the end of piston rod 99 and thus free the piston 92 and pin 99. If the pressure in the duct D by reason of failure of duct D, or excessive leakage has fallen sufiiciently to permit spring 94 to lift piston 92 and pin 99 so that the valve 89 is released, connection will be made between cylinder I0 and duct G. If, however, the pressure in line D has not failed, piston 92 will be held downwardly so that when piston I is lifted again, the bell crank I85 will rock in a counter-clockwise direction to permit arm 199 to lock the piston rod 93 against upward movement. A stop IIO limits the counter-clockwise movement of the bell crank.

Similarly, after duct D fails and duct G becomes effective, the slide valve 89 is moved to the left against the action of spring [90, and is held there by the pin 99 engaging the right hand end of the slide valve 89. The pin is moved down as the pressure builds up again (after D has failed) by the pressure supplied from duct G. The pin is held down by the action of the bell crank I05 except when the piston II approaches the lower end of cylinder I0.

In accordance with the provisions of the patent statutes, we have herein described the principle and operation of our invention, together with the apparatus which we now consider to represent the best embodiment thereof, but we desire to have it understood that the apparatus shown is only illustrative and that the invention can be carried out by other equivalent means. Also, while it is designed to use the various features and elements in the combination and relations described, some of these maybe altered and others omitted without interfering with the more general results outlined, and the invention extends to such use.

. Having described our invention, what we claim and desire to secure by Letters Patent is:

1. In a hydraulic remote control system, in combination, a transmitting station, a receiving station, a main force transferring connection between said stations, an auxiliary force transferring connection between said stations normally disconnected at both ends from said stations, means responsive to breaking of said main connection, and means actuated by said responsive means for connecting said auxiliary connection to said stations.

2. In a hydraulic remote control system, in

combination, a transmitting station, a receiving station, a main hydraulic force transferrin connection between said stations, an auxiliary force transferring connection between said stations normally disconnected at both ends from said stations, and means for disconnecting said main connection and connecting said auxiliary connection to said stations, said last-named means comprising manually operated means at one end of said auxiliary connection, means responsive to breaking of said main connection, and means at the other end of said auxiliary connection adapted to be actuated by said responsive means.

3. In a hydraulic remote control system, in combination, a transmitting station, a receiving station, a main hydraulic force transferring connection between said stations, including a variable volume chamber, an auxiliary hydraulic connection connected to said chamber and normally disconnected from said stations, means responsive to expansion and contraction of the fluid in said auxiliary connection for varying the volume of said chamber in a direction to compensate for variations in fluid volume in said main connection, and means for disconnecting said main connection and connecting said auxiliary connection to said stations.

4. In a hydraulic remote control system, in combination, a transmitting station, a receiving station, a main hydraulic force transferring connection'between said stations, including a variable volume chamber, an auxiliary hydraulic connection connected to said chamber and normally disconnected from said stations, means responsive to expansion and contraction of the fluid in said auxiliary connection for varying the volume of said chamber in a direction to compensate for variations in fluid volume in said main connection, and means for connectin said auxiliary connection to said stations when said main connection is broken.

5. In a hydraulic remote control system, in combination, a transmitting station, a receiving station, a main hydraulic force transferring connection between said stations, including a variable volume chamber, an auxiliary hydraulic connection connected to said chamber and normally disconnected from said stations, means responsive to expansion and contraction of the fluid in said auxiliary connection for varying the volume of said chamber in a direction to compensate for variations in fluid volume in said main connection, and means actuated by the breaking of said main connection for connecting said auxiliary connection to said stations.

6. In a hydraulic remote control system, in I combination, a transmitting station, a receiving station, a main hydraulic force transferring connection between said stations, including a variable volume chamber, an auxiliary hydraulic connection connected to said chamber and normally disconnected from said stations, means responsive to expansion and contraction of the fluid in said auxiliary connection for varying the volume of said chamber in a direction to compensate for variations in fluid volume in said main connection, and means for disconnecting said main connection and connecting said auxiliary connection to said stations, said last named means comprising manually operated means at one end of said auxiliary connection, and means at the 10 other end of said auxiliary connection adapted to be actuated by the breaking of said main connection.

7. In a hydraulic remote control system, in combination, a transmitting station, a receiving station, a main hydraulic force transferring connection between said stations, including a variable volume chamber, an auxiliary hydraulic connection connected to said chamber and normally disconnected from said stations, means responsive to expansion and contraction of the fluid in said auxiliary connection for varying the volume of said chamber in a direction to compensate for variations in fluid volume in said main connection, and means for disconnecting said main connection and connecting said auxiliary connection to said stations, said last named means comprising manually operated means at one end of said auxiliary connection, and means at the other end of said auxiliary connection adapted to be actuated by the operation of said manually operated means.

8. In a hydraulic remote control system, in combination, a transmitting station, a receiving station, a main hydraulic force transferring connection between said stations, including a variable volume chamber, an auxiliary hydraulic connection connected to said chamber and normally disconnected from said stations, means responsive to expansion and contraction of the fluid in said auxiliary connection for varying the volume of said chamber in a direction to compensate for variations in fluid volume in said main connection, and means for disconnecting said main connection and connecting said auxiliary connection I to said stations, said last named means comprising means adapted to be actuated by the breaking of said main connection for connecting one end of said auxiliary connection by way of said chamber, and manually operated means for connecting the other end of said auxiliary connecion.

9. In a hydraulic remote control system, in combination, a transmitting station, a receiving station, a main hydraulic force transferring con- REFERENCES CITED The following referernlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,987,435 Engel Jan. 8, 1935 2,107,111 Etchison Feb. 1, 1938 2,186,235 Brown Jan. 9, 1940 2,344,768 Dodson Mar. 21, 1944 

